ControlLogix troubleshooting answers
12 questions with answers cited from the manufacturer manuals.
- 0ControlLogix 5570 T07:C42 after controller swap, what to check?
A Major Fault T07:C42 on a ControlLogix controller indicates a revision mismatch. This means the project in the controller's nonvolatile memory has a different firmware revision than the controller itself. This fault typ…
- 0ControlLogix T07:C41 after replacing controller, what to check?
A Major Fault T07:C41 indicates a 'Load Type Mismatch' where the controller failed to load from nonvolatile memory because the project on the memory card was saved for a different controller type. This typically occurs a…
- 0ControlLogix L7x T07:C40: Store Failed after download, what to check?
A Type 7 Code 40 fault on a ControlLogix controller indicates that storing the project to the nonvolatile memory card failed. This can occur during a project store operation or after a download with the store-to-nonvolat…
- 0ControlLogix 5570 T06:C01: Task Watchdog Expired after program change, why?
A Type 6 Code 1 fault, or Watchdog fault, indicates that a user task did not complete within its allotted watchdog time. This often occurs after program changes that introduce new logic or loops, causing the task to take…
- 0ControlLogix T04:C83 fault in Run, what to check for Boolean array subscript?
A T04:C83 'Value Out of Range' major fault on a ControlLogix or CompactLogix controller indicates that a data value tested was outside its required limits. This specific fault type is associated with array subscripts use…
- 0ControlLogix T04:C34 (Timer Failure) after a recipe download, what to check?
A Major Fault T04:C34, also known as a 'Negative Timer' fault, indicates that a timer instruction in the Logix 5000 controller program received a negative value for its preset (.PRE) or accumulated value (.ACC). This fau…
- 0ControlLogix 5570 T04:C31: JSR/RET parameter count mismatch, what to check?
A ControlLogix or CompactLogix controller displays a Major Fault Type 4 Code 31 when a JSR instruction attempts to call a subroutine (SBR/RET) with fewer parameters than the subroutine expects. This fault occurs when the…
- 0ControlLogix 5570 T04:C20: Invalid Array Subscript in Run, what to check?
A ControlLogix or CompactLogix controller displaying a Major Fault T04:C20 indicates a program fault where an array subscript was too large for the array, or the .POS or .LEN value of a CONTROL structure was invalid. Thi…
- 0ControlLogix 5570 Major Fault T04:C16 after program download, what to check?
A Major Fault T04:C16, or 'Unknown Instruction', indicates the controller encountered an instruction it doesn't recognize during program execution. This typically happens after a program download, especially if the proje…
- 0CompactLogix 5380 T03:C23 at Run: what to check first?
A T03:C23 fault on a Logix 5000 controller indicates that a required I/O module connection was not established before the controller entered Run mode, within its configured time limit. This often occurs during the transi…
- 0CompactLogix 5370 T03:C16: I/O connection fault in Run mode, what to check?
A T03:C16 major fault on a Logix 5000 controller indicates that a connection to a required I/O module has failed while the controller was in Run mode. This fault occurs only if the module is configured to cause a major f…
- 0ControlLogix T01:C01 after power loss, what to check first?
A Type 1 Code 1 (T01:C01) fault on a ControlLogix controller indicates that the controller powered up in Run or Remote Run mode after a power loss. This fault prevents the controller from automatically returning to norma…